Various techniques are currently being used to provide electrical insulation between the winding of the armature coil and the armature core. Perkins, in U.S. Pat. No. 2,831,991 teaches the lamination of the ends of the armature core with insulating laminates which are fabricated separately and require individual handling during assembly.
Studer, in U.S. Pat. No. 2,232,812, discloses an armature insulating arrangement in which layers of insulating material covering each end of the armature core are formed integral with the core slot insulation. This layer of insulating material may be molded separately or molded directly onto the faces of the armature core.
Robison et al, in U.S. Pat. No. 3,917,967, discloses an armature insulation arrangement in which a molded insulating material is applied between the shaft the armature core and against the end faces of the armature coil to a diameter which is approximately equal to the root diameter of the slots in which the coil is wound, while Caillier, Sr., U.S. Pat. No. 4,663,835 teaches applying the insulation along the arms which extend radially on opposite sides of these slots.
As is evidenced by the prior art, a continuous effort is being exerted to improve the electrical insulation between the coil windings and the core on which these coils are wound.